U.N. weapons inspectors returned `` overwhelming and indisputable '' evidence of the use of nerve gas in Syria , Secretary-General Ban Ki-moon said Monday , calling the findings `` beyond doubt and beyond the pale . ''

The inspectors ' 38-page report was released after Ban briefed Security Council members on its contents . The team found what it called `` clear and convincing evidence '' that the nerve agent sarin was delivered by surface-to-surface rockets `` on a relatively large scale '' in the suburbs of the Syrian capital Damascus on August 21 .

`` It is the most significant confirmed use of chemical weapons against civilians since Saddam Hussein used them in Halabja in 1988 , and the worst use of weapons of mass destruction in the 21st century , '' Ban said . `` The international community has a responsibility to ensure that chemical weapons never re-emerge as an instrument of warfare , '' he said .

Ban called the attack `` a war crime '' and a violation of treaties banning the use of chemical weapons that date back to 1925 . But the inspectors ' mandate did not include assigning blame for the attack , and Ban would not speculate on who launched the attack .

The team did identify two types or rockets it said were used to deliver the gas and their trajectories , and international observers have said those weapons are not known to be in the hands of rebels battling the government of Syrian President Bashar al-Assad .

Australian U.N. Ambassador Gary Quinlan , who is currently serving as president of the Security Council , said the report bolsters his country 's stance . It `` confirms , in our view , that there is no remaining doubt that it was the regime that used chemical weapons . ''

Read the report

And Samantha Power , the U.S. ambassador , said a preliminary review of the report points toward forces loyal to al-Assad .

`` The regime possesses sarin , and we have no evidence that the opposition possesses sarin , '' Power said . `` It defies logic '' to think members of the opposition would have infiltrated a regime-controlled area to fire on opposition-controlled areas .

Britain , France , and NATO have also said al-Assad 's regime was behind the attack . But Russia is Syria 's leading ally , and Russian U.N. Ambassador Vitaly Churkin maintained Moscow 's stance that Syrian rebels might be to blame .

Such suggestions `` can not be simply shrugged off , '' Churkin said , and statements insisting that the opposition could not have launched the attack `` are not as scientific and grounded in reality as the actual situation could be . '' He questioned why rebel forces did n't report major losses in the August 21 chemical attack , which the United States says may have killed more than 1,400 , including hundreds of civilians .

Samples examined

The August 21 attack led to U.S. calls for military action against Syria , which denies its forces unleashed chemical weapons and blamed rebel fighters for the deaths . Syria has since agreed to join the 1993 Chemical Weapons Convention and hand over its chemical arsenal to international inspectors , with the United States and Russia laying out a fast-paced framework for Damascus to follow .

Monday 's report presents a stark picture of the damage that can be inflicted by a nerve agent like sarin , one of three types of poison gas Syria is believed to have stockpiled .

`` Survivors reported that following an attack with shelling , they quickly experienced a range of symptoms , including shortness of breath , disorientation , eye irritation , blurred vision , nausea , vomiting and general weakness , '' Ban said . `` Many eventually lost consciousness . First responders described seeing a large number of individuals lying on the ground , many of them dead or unconscious . ''

The weather made things worse . Falling temperatures at the time of the attack meant the downward movement of air , allowing the gas `` to easily penetrate the basements and lower levels of buildings and other structures where many people were seeking shelter , '' Ban said .

Inspectors interviewed survivors and first responders , collected hair , urine and blood samples and took soil and environmental samples from the sites where the rockets fell . The secretary-general said the team `` adhered to the most stringent protocols available for such an investigation , including to ensure the chain of custody for all samples . ''

More than 100,000 people had already been killed in Syria before August 21 , according to the United Nations . Another 2 million have fled the country , most of them taking refuge in Lebanon , Turkey , Jordan and Iraq .

It was not immediately clear how the report would affect events on the ground . The opposition Syrian National Coalition said the findings `` demand a unified and decisive response by the international community . ''

`` If the world does not act now , this war will continue , and thousands more will die , '' Najib Ghadbian , the coalition 's representative to the United Nations , said in a written statement . `` The people of Syria look to the U.N. Security Council to do everything in its power to stop this conflict and hold the Syrian regime responsible for its criminal actions . ''

In Washington , the White House announced that President Barack Obama would waive restrictions on exporting chemical protective gear to provide that equipment to the opposition and train `` select , vetted members '' in its use . American equipment will also be provided to the Organisation for the Prohibition of Chemical Weapons , the international body that monitors compliance with the Chemical Weapons Convention . It will be OPCW inspectors who are likely to carry out Syria 's promised disarmament .

Syria : There 's a chemical weapons agreement . Now what ?

Also Monday , Turkish fighter jets downed a Syrian helicopter near the border between the two countries Monday , Turkey 's semiofficial Anatolia News Agency reported , citing Deputy Prime Minister Bulent Arinc . Syria 's state news agency SANA said the helicopter was watching for `` terrorists '' crossing the border and erroneously strayed into Turkish airspace , but was on its way back across the border when shot down .

Russia slams U.S. remarks on agreement

Even as the world awaited the U.N. inspectors ' report Monday , Russia openly bickered with the United States about the agreement they struck in Geneva over the weekend .

The framework they laid out calls for a U.N. resolution demanding that Syria 's chemical weapons be placed under international control . Security Council powers are now trying to put that framework into a resolution . But Russian Foreign Minister Sergey Lavrov on Monday accused U.S. Secretary of State John Kerry `` and his Western allies '' of misunderstanding the deal , according to Russia 's state-run Itar-Tass news agency .

Lavrov said the deal does not say the U.N. resolution will be under Chapter VII of the U.N. charter , which potentially authorizes the use of force -- and comments by U.S. Secretary of State John Kerry that the any resolution will need to include the possibility of force `` show unwillingness to read the document '' that Russia and the United States endorsed .

The agreement states that if there is noncompliance `` or any use of chemical weapons by anyone in Syria , the U.N. Security Council should impose measures under Chapter VII of the U.N. Charter . '' But it does not specifically state that the resolution being sought now will be under that chapter .

Russia holds veto power on the council . But Kerry told reporters Monday that `` Should diplomacy fail , the military option is still on the table . ''

`` If the Assad regime believes that this is not enforceable , then they will play games , '' he said .

Framework for eliminating Syrian chemical weapons

According to the plan , Syria must submit a full list of its chemical weapons stockpile within a week . International inspectors must be on the ground in the country by November , and all production equipment must be destroyed by the end of November .

By the middle of next year , all chemical weapons material must be destroyed , according to the agreement . But the process of securing and destroying Syria 's cache of chemical weapons -- in the middle of a civil war -- may be a logistical nightmare .

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Syria findings `` beyond doubt and beyond the pale , '' Ban says

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U.S. to provide chemical protective gear to opposition , inspectors

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Sarin report demands `` a unified and decisive response , '' Syrian opposition says

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Syria says helicopter was shot down after straying into Turkish airspace